Conductance oscillations in mesoscopic rings: microscopic versus macroscopic picture

The phase of Aharonov-Bohm oscillations in mesoscopic metal rings in the presence of a magnetic field can be modulated by application of a DC-bias current I_DC. We address the question of how a variation of I_DC and hence of the microscopic phases of the electronic wave functions results in the macroscopic phase of the conductance oscillations. Whereas the first one can be varied continuously the latter has to be quantized for a ring in two-wire configuration by virtue of the Onsager symmetry relations. We observe a correlation between a phase flip by +/- pi and the amplitude of the oscillations.Comment: 4 pages, 4 figure

PHYCOBILISOMES AND ISOLATED PHYCOBILIPROTEINS. EFFECT OF GLUTARDIALDEHYDE AND BENZOQUINONE ON FLUORESCENCE

The fluorescence of the biliproteins C-phycocyanin from Spirulina platensis, B-phycoerythrin from Porphyridium cruentum and of isolated whole P. cruentum phycobilisomes is quenched in the presence of glutardialdehyde (GA) or benzoquinone (BQ). The kinetics of fluorescence decrease thus induced is biphasic. If GA is used as a quencher, the fluorescence can be recovered at 77 K. Contrary to the GA-effect, only a minor recovery takes place with BQ at 77K, thus demonstrating a different mechanism of action of GA and BQ on biliprotein

A case study of perceptions of value for students at a private, liberal arts college in the Midwestern United States

Dissertation supervisor: Dr. Carole Edmonds.Includes vita.Large amounts of quantitative data can be obtained by means of the National Survey for Student Engagement (NSSE). However, can a 15-minute survey truly provide an institution with enough relevant data to adequately understand a student's perception of value in order to help inform strategic changes that will affect future levels of engagement? Harper (2007) suggests that quantitative assessment has overwhelmed significant qualitative research efforts, limiting potential insights gained from a student's valuable first-hand experience. Whereas student success can be measured at the end of a semester, school year, or educational career, qualitative measurement of a student's perception of value reflect how their learning experience evolves over the course of their entire college experience. This qualitative bounded case study examines the perceptions of value for students at a private, liberal arts college in the Midwestern United States.Includes bibliographical references (pages 199-209)